1. Field of the Invention
The present invention relates to an image capturing lens system, and more particularly, to a compact image capturing lens system used in electronic products.
2. Description of the Related Art
The demand for compact imaging lens assembly has grown in recent years as the popularity of portable electronic products with the photographing function has increased. The sensor of a general photographing camera is none other than CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) sensor. Furthermore, as the advanced semiconductor manufacturing technology has allowed the pixel size of sensors to be reduced, and the current electronic products are leaning toward a trend of being more compact, there is an increasing demand for higher image quality.
The optical system of five lens elements such as the one disclosed in U.S. Pat. No. 8,000,030 is not functioning well in EDOF (Extended Depth of Field), and thereby is not easy to meet the requirement of higher image quality in creating large depth of field through focusing mechanism. In addition, the focusing lens driving devices such as the VCM (voice coil motor) is often employed for the optical system to focus, and this extra cost of the focusing lens driving devices will raise the manufacturing cost; accordingly, it is not favorable for mass production.
Inasmuch as the foregoing, the EDOF changes the conventional optical design thinking by combining the optical technology with the digital technology. The optical information is encoded and further decoded by the computer information technology in order to extend the depth of field for the optical system. Moreover, the auto-focus mechanism without having actual focusing components can obtain a larger depth of field under the premise of not reducing the luminous flux and not affecting the image quality. Therefore, in order to design an optical system which is suitable for compact and portable electronic products, it not only offers better auto-focus performance but also provides higher image quality with lower manufacturing costs. There is a need in this field for an optical system with a suitable convexity for the light focusing adjustment of various wavelengths in order to extend the depth of field and achieve excellent image quality within a proper total track length for image capturing lens system.